Transmitting a weather chart on a fisheries radio voice band, data size of a chart must be less than 3KB in order to keep the required time of a few minutes. Since it has over 340KB data size originally, we need to reduce the size by one hundredth. In this paper, we propose a new compression method for weather chart. Compared with the previous method, proposed method includes the following advantages. Implementation of error detection and feedback system, reducing computational cost by speeding up blanket method, and improvement of visibility by filtering process based on character features.